2.0 Nichols Creek Catchment: Surface Water Quality Conditions

Surface water quality conditions in the Nichols Creek Catchment are monitored by the City of Ottawa Baseline Water Quality Monitoring Program. This program provides information on the condition of Ottawa’s surface water resources; data is collected for multiple parameters including nutrients (total phosphorus, total Kjeldahl nitrogen and ammonia), E. coli, metals (like aluminum and copper) and additional chemical/physical parameters (such as alkalinity, chlorides, pH and total suspended solids). The locations of monitoring sites are shown in Figure 2 and Table 1.

Figure 2 Water quality monitoring site in the Nichols Creek catchment

2.1 Nichols Creek Water Quality Rating

The RVCA's water quality rating for Nichols Creek (site CK76-01) is “Fair” (Table 1) as determined by the Canadian Council of Ministers of the Environment (CCME) Water Quality Index. A “Fair” rating indicates that water quality is usually protected but is occasionally threatened or impaired; conditions sometimes depart from natural or desirable levels. Each parameter is evaluated against established guidelines to determine water quality conditions. Those parameters that frequently exceed guidelines are presented below. There is limited data available at this site prior to 2010, therefore only information for the 2010-2015 period will be discussed. Table 1 shows the overall rating for the monitored surface water quality site within the Nichol’s Creek Catchment and Table 2 outlines the Water Quality Index (WQI) scores and their corresponding ratings.

There is one monitored water quality site on Nichols Creek within this catchment (CK76-01, Figure 2). The score at this site is largely influenced by occasional high nutrient concentrations and bacterial pollution. For more information on the CCME WQI, please see the Jock River Subwatershed Report.

Table 1 Water Quality Index rating for the Nichols Creek Catchment

Sampling Site

Location

2010-2015

Rating

CK76-01

Nichols Creek upstream of O'Neil Rd culvert, north east of Dwyer Hill Rd.

2.2 Nutrients

Total phosphorus (TP) is used as a primary indicator of excessive nutrient loading and may contribute to abundant aquatic vegetation growth and depleted dissolved oxygen levels. The Provincial Water Quality Objective (PWQO) is used as the TP Guideline and states that in streams concentrations greater than 0.030 mg/l indicate an excessive amount of TP.

Total Kjeldahl nitrogen (TKN) and ammonia (NH3) are used as secondary indicators of nutrient loading. RVCA uses a guideline of 0.500 mg/l to assess TKN[1] and the PWQO of 0.020 mg/l to assess NH3 concentrations in the Jock River.

Tables 3, 4 and 5 summarize average nutrient concentrations at monitored sites within the Nichols Creek catchment and show the proportion of results that meet the guidelines.

Table 3 Summary of total phosphorus results for the Nichols Creek catchment, 2010-2015

Total Phosphorous 2010-2015

Site

Average (mg/l)

Below Guideline

No. Samples

CK76-01

0.012

98%

59

Table 4 Summary of total Kjeldahl nitrogen results for the Nichols Creek catchment from 2010-2015. Highlighted values indicate average concentrations exceed the guideline

Total Kjeldahl Nitrogen 2010-2015

Site

Average (mg/l)

Below Guideline

No. Samples

CK76-01

0.606

24%

59

Table 5 Summary of ammonia results for the Nichols Creek catchment from 2010-2015

Ammonia 2010-2015

Ammonia 2010-2015

Ammonia 2010-2015

Ammonia 2010-2015

Site

Average (mg/l)

Below Guideline

No. Samples

CK76-01

0.024

100%

59

Monitoring Site CK76-01

TP results seldom exceeded the PWQO at site CK76-01. Ninety-eight percent of samples were below the guideline (Figure 3). The average TP concentration was below the objective at 0.012 mg/l as shown in Table 3.

The bulk of TKN results were elevated (Figure 4); only 24 percent of samples were below the guideline in the 2010-2015 period. The average concentrations exceeded the guideline at 0.606 mg/l (Table 4).

The results for NH3 indicate that exceedances occurred occasionally. Seventy-one percent of results were below the guideline in 2010-2015 reporting period (Figure 5). The average NH3 concentration was 0.024 mg/l (Table 5) and just exceeds the PWQO.

Summary

Occasional nutrient enrichment is a feature in this reach of Nichols Creek. The elevated TKN concentrations and moderate NH3 results provide evidence that elevated nutrients may be a natural feature in this part of the creek, and are likely associated with the large wetland areas. Occasional exceedances of both NH3 and TP indicate that some nutrient loading may occur from upstream anthropogenic sources such as fertilizer use, agricultural activities and storm water runoff. Elevated nutrients may result in nutrient loading downstream and to the Jock River. High nutrient concentrations can help stimulate the growth of algae blooms and other aquatic vegetation in a waterbody and deplete oxygen levels as the vegetation dies off. Best management practices should be employed wherever possible to limit nutrient loading to the waterbody.

2.3 Escherichia coli

Escherichia coli (E. coli) is used as an indicator of bacterial pollution from human or animal waste; in elevated concentrations it can pose a risk to human health. The PWQO of 100 colony forming units/100 millilitres (CFU/100 ml) is used. E. coli counts greater than this guideline indicate that bacterial contamination may be a problem within a waterbody.

Table 6 summarizes the geometric mean[2] for the monitored site on the Nichol’s Creek within this catchment and shows the proportion of samples that meet the E. coli guideline of 100 CFU/100 ml. The results of the geometric mean with respect to the guideline 2010-2015 is shown in Figure 6.

Table 6 Summary of E. coli results for Nichols Creek, 2010-2015

E. coli 2010-2015

Site

Geometric Mean (CFU/100ml)

Below Guideline

No. Samples

CK76-01

33

73%

59

Monitoring Site CK76-01

Elevated E. coli counts at site CK76-01 were an occasional occurrence. The proportion of samples below the guideline was 73 percent (Figure 6). The geometric mean was 33 CFU/100ml (Table 6), and well below the PWQO of 100 CFU/100ml.

Summary

Bacterial pollution does not appear to be a significant problem at this site, the count at the geometric mean is well below the PWQO and the majority of samples do not exceed the guideline. Best management practices such as enhancing shoreline buffers, minimizing storm water runoff and restricting livestock access to creeks should be employed wherever possible to help to protect this reach of Nichols Creek into the future.

2A type of mean or average, which indicates the central tendency or typical value of a set of numbers by using the product of their values (as opposed to the arithmetic mean which uses their sum). It is often used to summarize a variable that varies over several orders of magnitude, such as E. coli counts